We are studying the efficacy of an immunosuppressive agent, cyclosporine A (CSA), in the treatment of severe, recalcitrant psoriasis and/or psoriatic arthritis unresponsive to existing therapies. The mechanism of action of CSA in psoriasis appears to be related to lymphocyte activity via an effect on inflammatory mediators (lymphokines). Using skin biopsies obtained before and after treatment, we are looking for the expression of lymphokine genes in lesional skin and studying the effect of CSA therapy on lymphokine production